1. Field of the Invention
The present invention relates generally to an imaging apparatus, and particularly to a cleaner assembly that includes an auger, a drive shaft, and a waste toner storage container for moving and storing waste toner within a printer cartridge.
2. Description of the Related Art
In the electro photography process, toner is transferred from a developer roll to a photoconductive drum and then to an intermediate transfer belt. When the toner has poor transfer characteristics, the toner is not transferred from the photoconductive drum to the intermediate transfer belt and remains on the photoconductive drum. The toner that remains on the photoconductive drum is referred to as waste toner. It is desirable to remove the waste toner from the photoconductive drum. One way to remove the waste toner from the photoconductive drum is to use a cleaner blade. While the waste toner is being removed, the waste toner falls into a channel behind the photoconductive drum. However, the capacity of the channel may not be enough to accommodate the amount of the waste toner that is produced during life of the printer cartridge. This creates a need for a mechanism that moves the waste toner from the channel and stores the waste toner in a different storage area of the printer cartridge where more space is available.
Generally, an auger that is housed in the channel is utilized for transferring the waste toner from the channel to a storage area in the printer cartridge. The auger is driven by a photoconductive drum drive and keeps rotating during the printing process to prevent accumulation of the waste toner in the channel behind the photoconductive drum. An end of the channel opens into the storage area that is generally referred to as a waste toner storage container. FIG. 1 illustrates a cross sectional view of the auger/waste toner storage container design according to a prior art system explaining the mechanism to move the waste toner into the waste toner storage container. After the waste toner is removed from the photoconductive drum, the waste toner is guided into a channel 20. During the printing process, a drive gear 24 attached to an auger 22 receives a driving force due to which the auger 22 is turned in a direction that pushes the waste toner towards the waste toner storage container 28 (movement of the waste toner shown by arrow 26). This creates sufficient room inside the channel 20 to receive a fresh supply of the waste toner from the photoconductive drum.
Current design architecture oftentimes requires that the waste toner enters into the waste toner storage container 28 from a location that is closer to the bottom of the waste toner storage container. The auger 22 is straight and terminates just inside the waste toner storage container 28. The auger 22 can push the waste toner only along its axis, so the waste toner gets pushed straight into the waste toner storage container 28 instead of being directed towards the top of the waste toner storage container 28. The auger 22 is therefore required to push an ever increasing amount of the waste toner up through the waste toner storage container 28 in order to fill it entirely. Such design of the waste toner storage container 28 and location of the auger 22 builds up unwanted pressure around end of the auger 22.
Further, poor toner flow characteristics pose another problem. When a portion of the waste toner storage container 28 is filled up to height of the auger 22, the waste toner compacts around the auger 22 instead of flowing into areas of lower pressure, i.e., a portion of the waste toner storage container that is at a height above the location of the auger. As discussed, the auger 22 can only force toner in its axial direction, so the auger 22 forces the waste toner straight into the backside of waste toner storage container 28. This results in the waste toner being densely compacted around the auger 22 even though the waste toner storage container 28 is not fully filled.
As pressure around the auger 22 increases, torque on the auger 22 also increases. The pressurized waste toner creates a resistance in the rotation of the auger 22 that increases the stress on drive components of the auger 22. This causes gear teeth on the drive gear 24 to shear or slip over one another. This failure of the drive components may occur even though the waste toner storage container 28 is not fully filled. Additionally, the torque continuously changes through the life of the printer cartridge as the auger 22 is required to force the waste toner up through highly compacted layers of the waste toner. Even before the auger 22 fails, this continual increase in the torque during the life of printer cartridge results in noise that is undesirable to a user. The noise results from the auger 22 being loaded to a point that the auger 22 begins to rub against the channel 20, even though the printer cartridge is still fully operable.
Thus, there is a need to improve the auger/waste toner storage container design. It is desired to utilize substantially all the available space inside the waste toner storage container. By filling substantially all of available space, one may more efficiently utilize the waste toner storage container and further decrease the likelihood of the printer cartridge failure as discussed above. It is further desired to create an auger scheme whereby the torque on the auger remains relatively low during the life of the printer cartridge so that the noise concerns are more adequately addressed.